1. Field of the Invention
The invention relates to a connector of the input/output type with grounded shielded cables, and more particularly to a connector whose inputs/outputs are cables of the coaxial type or of the type called xe2x80x9ctwinaxxe2x80x9d, or similar cables.
The invention also relates to a method of producing such a connector.
2. Discussion of Background
The structure of a conventional coaxial cable comprises a central conductor, called the core, consisting of a solid wire, generally made of copper. The central core is surrounded by an electrically insulating dielectric which separates the core from an external cylindrical screen, generally a metal braid, forming a second conductor of a pair. The assembly is surrounded by a protective sheath made of electrically insulating material. More complex structures exist, comprising several central conductors and at least one metal screen, for example the structure called xe2x80x9ctwinaxxe2x80x9d structure comprising two solid central conductors. In the following, in order to be more concrete, the example of coaxial cables will be considered, without thereby limiting the scope of the invention.
One of the standard applications of such cables is the transmission of high-frequency AC or pulsed signals. Thus, coaxial cables or the like are associated with a number of critical electrical characteristics namely, in particular, the characteristic impedance, the operating frequency range, the attenuation, the reflection coefficient or standing wave ratio (SWR), etc. Furthermore, it is often necessary to connect the coaxial cable shields to the mechanical ground of the electrical and/or electronic items of equipment or apparatus in which they are used, so that the signals are defined with respect to a well-defined potential.
In many items of equipment, either because they are mobile or because they must themselves communicate with mobile, or at the very least disconnectable, apparatus, penetration connectors, of the complementary, male and female, type, are provided. Each pair of connectors establishes a connection of the coaxial type (or multi-coaxial type if there are several output cables per connector). Advantage is then taken of the presence of these connectors to fulfill the xe2x80x9cgroundingxe2x80x9d function of the coaxial cables which pass through them.
This is because certain connectors, called xe2x80x9cequipmentxe2x80x9d connectors, are provided with members which connect the outer metal shield of the coaxial contacts of various sizes to the metal body of the connector itself. In the term of the art, connectors of this type, which make it possible to fulfill the aforementioned grounding function, are often called xe2x80x9cgroundingxe2x80x9d connectors. The ground continuity provided by them, between the item of equipment and the shield (braid) of the cable, must in general be less than 10 mxcexa9.
Although connectors of the aforementioned type allow both functions (signal transmission and grounding) to be fulfilled, they are not thereby without drawbacks. From the standpoint of use on an industrial scale, they have in particular the following major drawbacks:
they have a high cost, typically about 2 to 3 kF, which cost must be compared with connectors of the same family (that is to say connectors having equivalent functions, apart from grounding), i.e. typically about 0.5 kF (namely in a ratio of about 1 to 5);
in many cases, there is only a single source of supply (a single manufacturer and/or distributor), something which is not generally acceptable as there is then a serious risk of running out of stock;
correspondingly, the continuity of supply is low, when it relies on the existence of a single source of supply;
supply lead times are generally long, typically around 6 to 8 months; and
connectors fulfilling the two aforementioned functions are not found in many families of xe2x80x9cequipmentxe2x80x9d-type connectors, thereby restricting the choice of models.
There is therefore a need for connectors having at least one output per coaxial cable or the like, fulfilling the function of connecting the outer metal shield of the cable or cables to the mechanical ground of the item of equipment supporting the connector, but not having the drawbacks of the devices of the prior art, some of which have just been mentioned.
To do this, the connectors according to the invention are provided with a specific member making it possible, in particular:
to provide the aforementioned grounding function;
to be able to fit with all standard connector families, whether of circular or rectangular overall shape;
to take up a minimum amount of volume at the rear of the connector;
to be easy to connect and disconnect;
to incur only a small additional cost compared with a standard connector not providing the grounding function; and
to provide ground continuity of less than 10 mxcexa9, as in the prior art.
The aforementioned member is based on a single and simple component consisting of a metal reinforcement, which will hereafter be called a xe2x80x9cfoilxe2x80x9d, comprising a part surrounding the connector and extensions placed between the connector and the mechanical structure of an item of equipment which supports this connector. More specifically, the foil is mounted so as to be gripped between the mechanical structure of the item of equipment, which supports a standard connector, and this connector. In general, the equipment has a plane wall provided with an opening intended to accommodate the body of the connector and means for fastening the latter. The front of the connector allows mechanical and electrical coupling to a connector of complementary type. The coaxial cable or cables emerge at the rear of the body of the connector, from and to other members internal to the item of equipment. The front part of the coaxial cables is provided with contacts, which are also coaxial, intended to house contacts of complementary type.
Even more specifically, the foil itself comprises a wall surrounding the rear of the connector and being extended toward the front by lateral flanges, preferably consisting of tabs, the tabs themselves having bent-over end parts gripped between the front of the body of the connector and the rear of the support wall of the item of equipment. The rear wall of the foil has one or more holes. Slipped into each hole is a coaxial cable or the like, forming one of the inputs/outputs of the connector. Each coaxial cable is stripped, as required, at these holes and is soldered to the foil.
It follows that the aforementioned member or xe2x80x9cfoilxe2x80x9d properly meets the objectives that the invention has set itself:
it fulfills the grounding function, with a typical galvanic continuity of less than or equal to 2.5 mxcexa9;
the additional volume at the rear of the connector, owing to the arrangements of the invention, is very small;
such a member is easy to connect and/or disconnect, as will be shown in further detail; and
the additional cost owing to the invention is low, whether in terms of additional material needed or in terms of additional cost during the manufacturing process (the manufacturing steps specific to the invention not being very complex).
The subject of the invention is therefore a connector of the type comprising a main body of defined shape, fastening means and at least one input and/or output with a cable having at least one external shield and leaving via one face, called the rear face, of the connector, said connector being intended to be mounted in a wall made of electrically conducting material of an item of electrical and/or electronic equipment and secured to this wall by said fastening means, characterized in that each of said external shields of the cables is made accessible from the outside in a defined region of the end of said cable close to said rear face, in that it includes a reinforcement made of electrically conducting material having at least one rear wall provided with as many holes as there are cables, so that it can be slipped over the cables, and lateral flanges having end parts bent over the cables inward and intended to be inserted and gripped between said fastening means and said wall made of electrically conducting material, when the connector is secured to this wall, and in that said regions of said shield which are accessible from the outside are electrically coupled to said rear wall of the reinforcement at said holes, so as to establish electrical continuity between said wall made of electrically conducting material and said shield when the connector is secured to this wall.
The subject of the invention is also a method of producing such a connector.